支付宝中的手机网站支付接口，php版notify_url.php异步通知页面未成功执行

verifyNotify();
if($verify_result) {//验证成功
 $notify_data = $alipayNotify->decrypt($_POST['notify_data']);
  $doc = new DOMDocument();
 $doc->loadXML($notify_data);
  if( ! empty($doc->getElementsByTagName( "notify" )->item(0)->nodeValue) ) {

  $out_trade_no = $doc->getElementsByTagName( "out_trade_no" )->item(0)->nodeValue;

  $trade_no = $doc->getElementsByTagName( "trade_no" )->item(0)->nodeValue;

  $trade_status = $doc->getElementsByTagName( "trade_status" )->item(0)->nodeValue;
    if($_POST['trade_status'] == 'TRADE_FINISHED' || $_POST['trade_status'] == 'TRADE_SUCCESS') { 
  //以下是数据库操作代码 
   require_once('../Connections/coon.php');
   mysql_select_db($database_coon, $coon);
   mysql_query("UPDATE shop_orders SET ZT='payed' WHERE DDH='$out_trade_no'");
   mysql_close($coon); 
//数据库操作结束
   echo "success"; 
  }
 }
}
else {
    echo "fail";
}
?>